Is it only if you load tabs ?? if you go to all those location manually it works ?
If i go to such a location the CPU Usage will faster finished, but need also very much more time than normal.
Also if all icons in cache run it ca 15 min. But if it this 15 min finished, it is able to load this session without this issue. After restarting MC it need 15 min again. MC32 bit Edition 7.5 need for the same a half minute.
Also the creating of the icon cache need a long time, i guess 5 min. But maybe it have nothing to do with the icon cache, because after the icon cache finished it take 10 min CPU Time. It use only 1 Core for this.